The present invention relates to transmission apparatuses and communication systems, and can be favorably applied to, for example, a near-field wireless communication.
A near-field wireless communication technology using the non-contact coupling of a pair of coupling elements is well-known. The non-contact coupling of the pair of coupling elements includes a magnetic coupling (inductive coupling) or an electrical coupling (capacitive coupling). The near-field wireless communication technology using the non-contact coupling have an advantage in that a high data rate can be implemented in an ultra-short distance (for example, several tens of micrometers to several centimeters) communication. Nonpatent Literature 1 (N. Miura et al., “Analysis and Design of Inductive Coupling and Transceiver Circuit for Inductive Inter-Chip Wireless Superconnect”, IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 40, NO. 4, April 2005, pp. 829-837) discloses a communication system in which a baseband signal transmission using a transmission line including a magnetic coupling of a pair of inductors (referred to a magnetic coupling transmission line hereinafter) is performed. In addition, Nonpatent Literature 1 discloses a theoretical analysis using an equivalent model of a magnetic coupling and also discloses that the gain of a magnetic coupling transmission line (voltage transfer function S21) shows a high-pass filter characteristic. FIG. 1 shows the frequency characteristic of the gain of the magnetic coupling transmission line disclosed in Nonpatent Literature 1.
Nonpatent Literature 2 (Jared L. Zerbe et al., “Equalization and Clock Recovery for a 2.5-10-Gb/s 2-PAM/4-PAM Backplane Transceiver Cell”, IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 38, NO. 12, December 2003, pp. 2121-2130) and Nonpatent Literature 3 (James F. Buckwalter et al., “Phase and Amplitude Pre-Emphasis Techniques for Low-Power Serial Links”, IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 41, NO. 6, June 2006, pp. 1391-1399) disclose pre-emphasis technologies that are applied to PAM (Pulse Amplitude Modulation) transmissions performed via wire transmission lines. To put it concretely, Nonpatent Literatures 2 and 3 disclose FIR (Finite Impulse Response) filter-type pre-emphasis circuits (that is, transmission equalizers) disposed in transmitters. For example, Nonpatent Literature 3 discloses that a symbol-spaced FIR filter or a half-symbol-spaced FIR filter is used as a transmission equalizer for correcting an ISI (Inter Symbol Interference) and a DDJ (Data-Dependent Jitter).